Epstein-Barr virus (EBV) is a member of the family Herpesviridae. EBV nucleic acid is double-stranded and consists of 172 Kb. EBV DNA is in a linear form in mature infectious virus particles and is in a circular episomal form in cells latently infected with the virus. EBV is the major cause of infectious mononucleosis, an acute, generally benign lymphoproliferative disease. Infection with EBV usually occurs by 10 years of age; 70 to 90% of children have been infected with EBV. Usually, infection in children is asymptomatic or mild and may be associated with minor illnesses such as upper respiratory tract infection, pharyngitis, tonsillitis, bronchitis, and otitis media. Other persistent EBV infections, such as those accruing in patients during the post-transplantation period, are common.
EBV has become a recognized cause of central nervous system infection and lymphoproliferative disorders (PTLD), and AIDS-related lymphomas. PTLD consists of a heterogenous group of B-cell neoplasias that arise in a setting of immunosuppression and are associated with EBV infection especially in patients lacking antibodies to this virus. The incidence of PTLD ranges from 1% for renal transplant recipients, but can be as high as 9% for heart/lung and 12% for pancreas transplant patients. EBV DNA can be detected in blood lymphocytes from patients with EBV infection, and quantitative evaluation of EBV DNA has been shown to correlate highly with the subsequent (3-4 month) development of PTLD in susceptible patients.